Barite Precipitation on Suspended Organic Matter in the Mesopelagic Zone

Mechanisms underlying barite precipitation in seawater and the precise depths of barite precipitation in the water column have been debated for decades. Here we present a detailed study of water column barite distribution in the mesopelagic zone at diverse stations in the open ocean by analyzing samples collected using multiple unit large volume in-situ filtration systems in the Pacific, Atlantic and Indian oceans. Our results demonstrate that barite is an organo-mineral particularly abundant at intermediate depths throughout the world’s ocean regardless of saturation state with respect to barite. This is confirming the notion of precipitation at depths of intense organic matter mineralization. Our observations further support the link between barite formation and microbial activity, demonstrated by the association of barite particles with organic matter aggregates and with extracellular polymeric substances. Evidence for microbial mediation is consistent with previous experimental work showing that in bacterial biofilms Ba binds to phosphate groups on cell surfaces and within extracellular polymeric substances. This organoaccumulation promotes high concentrations of Ba leading to saturated microenvironments and nucleation sites favoring precipitation. The distribution of Ba isotopes in the water column and in particulate matter is also consistent with the proposed precipitation mechanism.European Union (EU)Agencia Estatal de Investigacion, Ministerio de Ciencia e Innovacion, Spain CGL2017-92600-EXP PID2019-104624RB-I00Junta de Andalucia RNM-179 BIO 103 P18-RT-3804 P18-RT-4074Unidad Cientifica de Excelencia (University of Granada) UCE-PP2016-05 OCE-144357

Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

10 páginas, 5 figuras, 1 tabla.A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G) and terrestrial (Zoñar Lake, Andalucia, Spain) geochemical proxies provides a high-resolution reconstruction of climate variability and human influence in the southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our combined terrestrial and marine archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. A dry period occurred prior to 2.7 cal ka BP – synchronously to the global aridity crisis of the third-millennium BC – and during the Medieval Climate Anomaly (1.4–0.7 cal ka BP). Wetter conditions prevailed from 2.7 to 1.4 cal ka BP. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity than the Medieval Climate Anomaly. Additionally, Pb anomalies in sediments at the end of the Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The Late Holocene climate evolution of the in the study area confirms the see-saw pattern between the eastern and western Mediterranean regions and the higher influence of the North Atlantic dynamics in the western Mediterranean.Projects LIMNOCLIBER REN 2003-09130- C02-02, CALIBRE CGL 2006-13327-c04/CLI, CGL-2006-2956- BOS, CGL2009-07603 (MICINN), 200800050084447 (MARM) and RNM 05212 (Junta de Andalucía), we also thanks Projects GRACCIE (CSD2007- 00067) and CTM2009-07715 (MICINN), Research Group 0179 (Junta de Andalucía) and the Training- Through-Research Programme.Peer reviewe

A chromosome-level genome assembly enables the identification of the follicule stimulating hormone receptor as the master sex-determining gene in the flatfish Solea senegalensis

Sex determination (SD) shows huge variation among fish and a high evolutionary rate, as illustrated by the Pleuronectiformes (flatfishes). This order is characterized by its adaptation to demersal life, compact genomes and diversity of SD mechanisms. Here, we assembled the Solea senegalensis genome, a flatfish of great commercial value, into 82 contigs (614 Mb) combining long- and short-read sequencing, which were next scaffolded using a highly dense genetic map (28,838 markers, 21 linkage groups), representing 98.9% of the assembly. Further, we established the correspondence between the assembly and the 21 chromosomes by using BAC-FISH. Whole genome resequencing of six males and six females enabled the identification of 41 single nucleotide polymorphism variants in the follicle stimulating hormone receptor (fshr) consistent with an XX/XY SD system. The observed sex association was validated in a broader independent sample, providing a novel molecular sexing tool. The fshr gene displayed differential expression between male and female gonads from 86 days post-fertilization, when the gonad is still an undifferentiated primordium, concomitant with the activation of amh and cyp19a1a, testis and ovary marker genes, respectively, in males and females. The Y-linked fshr allele, which included 24 nonsynonymous variants and showed a highly divergent 3D protein structure, was overexpressed in males compared to the X-linked allele at all stages of gonadal differentiation. We hypothesize a mechanism hampering the action of the follicle stimulating hormone driving the undifferentiated gonad toward testisEuropean Union's Horizon 2020 research and innovation programme under grant agreement (AQUA-FAANG). Grant Number: 81792. Junta de Andalucía-FEDER Grant. Grant Number: P20-00938. Spanish Ministry of Economy and Competitiveness, FEDER Grants. Grant Numbers: RTI2018-096847-B-C21, RTI2018-096847-B-C22S

Challenge 1: Past global changes: a context to the Anthropocene

Facing current climate and environmental crises needs long-term series of Earth Dynamics and anthropogenic pressures on the Planet. Numerous geological, chemical and biological natural archives capture large-scale, multi-temporal, abrupt, and often irreversible shifts in environmental and climate systems, providing an opportunity to better understand and therefore predict potential future impacts of the present anthropogenic warming and Humankind impact on the Planet. By providing robust, reliable, quantitative, detailed, high-resolution and long paleoclimate and paleoenvironmental data series, paleoclimatology and paleoenvironmental research place present climate variability and ecological crises in a long-term perspective to understand climate forcing mechanisms and environmental processes and responses. The success of science-based solutions to the global risks in the 21st century will strongly rely on our capacity to transfer this knowledge to politicians, managers, and society.Peer reviewe

Extinction risk of Mesoamerican crop wild relatives

Ensuring food security is one of the world's most critical issues as agricultural systems are already being impacted by global change. Crop wild relatives (CWR)—wild plants related to crops—possess genetic variability that can help adapt agriculture to a changing environment and sustainably increase crop yields to meet the food security challenge. Here we report the results of an extinction risk assessment of 224 wild relatives of some of the world's most important crops (i.e. chilli pepper, maize, common bean, avocado, cotton, potato, squash, vanilla and husk tomato) in Mesoamerica—an area of global significance as a centre of crop origin, domestication and of high CWR diversity. We show that 35% of the selected CWR taxa are threatened with extinction according to The International Union for Conservation of Nature (IUCN) Red List demonstrates that these valuable genetic resources are under high anthropogenic threat. The dominant threat processes are land use change for agriculture and farming, invasive and other problematic species (e.g. pests, genetically modified organisms) and use of biological resources, including overcollection and logging. The most significant drivers of extinction relate to smallholder agriculture—given its high incidence and ongoing shifts from traditional agriculture to modern practices (e.g. use of herbicides)—smallholder ranching and housing and urban development and introduced genetic material. There is an urgent need to increase knowledge and research around different aspects of CWR. Policies that support in situ and ex situ conservation of CWR and promote sustainable agriculture are pivotal to secure these resources for the benefit of current and future generations

The role of exopolymeric substances in mineral precipitation: implications for the geological record and Earth System evolution

First meeting on Biophysical approaches to exopolymeric particle dynamics in aquatic ecosystems, Granada (España), June 26th-27th 201

Transmission electron microscopy evidence for experimental illitization of smectite in K-enriched seawater solution at 50°C and basic pH

11 páginas, 9 figuras, 3 tablas.Experimental illitization of smectite was studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Experiments were performed on the <2 µm fraction consisting entirely of smectite separated from a soil formed on subvolcanic rock located in the External Zone of the Betic Cordilleras (southern Spain). Amounts of 0.25 g were added to different solutions: seawater, and three K-enriched seawater solutions prepared by adding KOH to seawater whose final [K] values were 0.1, 0.5 and 1 M, respectively. The experiments were performed at 50°C over a period of 30 days. The XRD patterns showed no mineralogical changes in residues from seawater or from the 0.1 M [K] solution. With increasing pH and K molarity, the smectite peak, initially at 1.4 nm, became broader. This change in the smectite peak was more significant in the residue from the 1 M [K] solution. The appearance of a small shoulder at 1.0 nm in the residue from a 0.5 M [K] solution showed the beginning of illite formation. However, its appearance was clearer in XRD patterns of the residue corresponding to the 1 M [K] solution. The XRD data from air-dried, glycolated, and heated samples from the 1 M [K] solution indicated the presence of smectite, disordered interstratified illite-smectite (I-S) and illite. The TEM/AEM studies were performed on the residue corresponding to the 1 M [K] experiment. The HRTEM images revealed that smectite and illite occurred as separated packets with a ferroan lizardite, as a by-product of the smectite-to-illite reaction, interstratified and intergrown with illite. Smectite occurs both as ‘rims’ on the illite packet and in its core. The presence of smectite in the core of illite packet indicates that the lateral transition from smectite to illite was incomplete, taking place by direct replacement of smectite layers as a whole through a dissolution-precipitation mechanism. The experimental study shows that smectite may transform in a wide range of geological and artificial environments involving high-pH K-rich solutions.Financial support was supplied by Research Project nº BTE 2000-0582 of the Spanish Ministry of Science and Technology, Research Group RNM-0179 of the Junta de Andalucia and the REN2001-3868 and REN 2000-0798 projects.Peer reviewe

Some clues about the Napoli and Milano mud volcanoes from an integrated log-core approach

A full set of conventional logging data and Formation MicroScanner (FMS) data were acquired on the flanks of the Milano mud volcano and the Napoli mud volcano on the Mediterranean Ridge, and provide a complete and continuous record of the petrophysical and geological features of these structures. On the basis of the logging data, and of mineralogical and geochemical sample analyses, the composition, sedimentation, and internal sedimentary and structural features of the mud volcanoes were studied. Conventional logging data indicate composition and/or texture-related variations and indicate different sedimentation episodes. These changes are also recognizable on FMS images. Layered intervals are identified at different depths within both mud volcanoes. Most features that are recognized, possible bedding surfaces, dip to the west to northwest in the Milano mud volcano and to the north-northwest and north-northeast in the Napoli mud volcano. The dip of the beds is consistent with gravitational deposition and the present-day morphology of the Napoli mud volcano. The dip and strike of inferred bedding features at the Milano mud volcano suggest either the existence of a depositional slope and a source of gravitational flows to the east, or tilting of the bedding surfaces by subsidence after deposition. Steeply dipping planes (>45°) that dip north-northwest at Napoli are likely to represent fractures. These features are recognized as electrically resistive features indicating that they are filled with a nonconductive material, possibly either halite or gas. The results of core sample analysis indicate that diagenetic mineralogical transformations have not affected the mud volcano material, that the clay minerals are of detrital origin, and that Fe-Al-rich smectites are predominant.The research of Jurado-Rodríguez was supported by a European Union HCM (ERB4001GT933623) grant and that of Martínez-Ruiz by a research grant of the Junta de Andalucía Research Group RNM-0179.Peer Reviewe

Rare earth element composition as evidence of the precursor material of Cretaceous-Tertiary boundary sediments at distal sections.

1 table, 2 figures.The Chicxulub impact event led to a worldwide deposition of impact materials originated from target rocks and the vaporized bolide. Relative contributions of both types of material to the K/T ejecta deposits vary with distance to the crater site. At distal sites (e.g., Agost and Caravaca in the SE of Spain) a major contribution of extraterrestrial material is indicated by different impact signatures, such as Os and Cr isotope composition, abundant microkrystites, platinum group elements and other siderophile elements that are typical of extraterrestrial components. Closer settings to the Chicxulub crater, for example the Blake Nose Plateau in the North American margin, display major continental crustal rock contributions in the ejecta layer. REE compositions provide additional evidence for terrestrial vs. extraterrestrial rock contributions. Previous research has not focused specifically on REE concentrations and corresponding C1- and NASC-normalized patterns. However, normalized REE patterns are already generating supplementary insights into the nature of the original material of the K/T boundary layer. Thus, Blake Nose ejecta C1-normalized patterns indicate a derivation from continental crustal target rocks. In more distal sections REE compositions point to a probable mafic precursor and confirm that extraterrestrial materials represent a major contribution the ejecta layer.This work was supported by Research Groups RNM-179 and RNM-190, Project RNM 432 (Geochemical proxies for environmental reconstruction: Implications for global change, Junta de Andalucía, Spain) and Projects BET-2000-1493 and REN-2003-09130-CO2-01 (MEC, Spain). The authors are grateful to the Leg 171B Shipboard Party, the crew of the Joides Resolution and the ODP Bremen Core Repository for their assistance with the samples. Thanks to the C.I.C (University of Granada, Spain) for the use of their analytical facilities. Thorough editing of the original English manuscript was done by Marco Bettini. We also thank P. Claeys and one anonymous reviewer for constructive reviews and the improvement of this paper.Peer reviewe